The structural disordering of face-centered cubic (110) surfaces was formulated in terms of a system of interacting domain walls which represented the elementary defects of the flat surface: (111) steps. The method was general, and could be extended to systems such as the face-centered cubic (111) surface. The theory exploited the method of approximately mapping the 2-dimensional statistical mechanics problem onto a 1-dimensional Fermionic Hamiltonian. In the present case, 2 Fermionic bands (multiple-hopping, short-range finite interactions) had to be included. The phase diagram of a recently proposed extended body-centered solid-on-solid model for noble-metal face-centered cubic (110) surfaces was derived by means of a mean-field calculation of the ground-state energy of the quantum Hamiltonian. This offered the advantage of reproducing the exact classical ground-state structure. Good agreement with previously obtained Monte Carlo simulation results for the solid-on-solid model was obtained. This indicated that the present treatment was qualitatively, and semi-quantitatively, correct with regard to the phase structure. Deconstruction, pre-roughening and roughening transitions were detected and the criteria for their occurrence were expressed in terms of microscopic step-step interaction parameters.

G.Jug: Philosophical Magazine B, 1996, 73[4], 555-83